Demisexuals are characterized by a lack of sexual attraction toward any person unless they become deeply emotionally or romantically connected with a specific person or persons. The level of connection it takes for sexual desire to form is dependent on how close the relationship is rather than initial attraction. It is an orientation that is not chosen.

Demisexuality does not refer to the active restraint or repression of sexual desires or actions.

Demi- is a prefix meaning half. This is used to mean halfway between sexual and asexual. The term originated in the asexual community, specifically within the Asexual Visibility and Education Network (AVEN).

Sexual partner: Hey, I think you are sexy. *aroused*
Demisexual partner: I'd have to reach a higher level of emotional intimacy before I could feel the same way. =\
Sexual partner: Oh, I see. Well, we can do something enjoyable together. =/
Demisexual partner: =D We can bake a cake for now!
Sexual partner: Sure! That's always fun, although we seem to be doing that a lot. =D
Demisexual partner: *squeee! bonding time!*

A demisexual is neither primarily attracted to either sex, nor do they primarily desire to have sex. This means that a romantic demisexual is someone who, in layman's terms, looks for personality over sex by nature.

Primarily, the human will not be attracted to another human, but after being with another human romantically, feelings may begin to develop. This is further elaborated upon by Rabger's Model, which suggest human sexuality is created by four factors: Primary/Secondary Sexual attraction and Primary/Secondary Sexual desire.
Demisexuality is (apparently) a form of asexuality, related to gray-a.

people who are attracted to those that they are close with / after a 'personal bond' is formed
this is similar to asexuality.
also, this is not the same as 'what a normal relationship is.' for example, a demisexual would feel uncomfortable on a blind date or being asked out by someone they dont know very well.

Someone who can't be physically be sexually attracted (Or sometimes never aroused) to someone without being romantically attached. It's basically impossible. No, If you WE'RE demi-sexual you wouldn't get wet panties over every 'attractive' male ever.

Some people over-use it like every other word.

Hi I'm demisexual, Which means I physically can't be sexually attracted to someone without being romantically attached to them. I am a completely normal person, Just like everyone else is.

A term coined by "special snowflake" SJW's to imply that they aren't sexually attracted to their partner until they have reached a particular level of "emotional intimacy". Otherwise known as being entirely normal.

-"I've been thinking lately, man.. I am straight, but I don't feel *special* enough."
-"Well, those weird kids on tumblr came up with this thing called being 'demisexual', you could always try that."
-"you know, I think i might be a demisexual."
-"I tell people i'm demisexual so they will at least think i'm crazy instead of just socially awkward. or god forbid, NORMAL. *shudders*"